The “testing effect,” as it's called by cognitive psychologists, seems pretty obvious to faculty. If students are going to be tested on material, they will learn it better and retain it longer than if they just study the material. And just in case you had any doubts, lots of evidence has been collected in labs and simulated classrooms that verifies the existence of this testing effect. But as with much of the research done in cognitive psychology, it has not been studied much in actual classrooms, and of specific interest here, in college classrooms. When it has been studied in college classrooms, the results aren't as consistent as might be expected, but then the study designs aren't all that similar.